docs: networking: convert tc-actions-env-rules.txt to ReST

- add SPDX header;
- add a document title;
- use the right numbered list markup;
- adjust identation, whitespaces and blank lines where needed;
- add to networking/index.rst.
Signed-off-by: NMauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Documentation/networking/index.rst

@@ -106,6 +106,7 @@ Contents:
    skfp
    strparser
    switchdev
+   tc-actions-env-rules
 
 .. only::  subproject and html
 

Documentation/networking/tc-actions-env-rules.txt → Documentation/networking/tc-actions-env-rules.rst

+.. SPDX-License-Identifier: GPL-2.0
+
+================================
+TC Actions - Environmental Rules
+================================
+
 
 The "environmental" rules for authors of any new tc actions are:
 
 1) If you stealeth or borroweth any packet thou shalt be branching
-from the righteous path and thou shalt cloneth.
+   from the righteous path and thou shalt cloneth.
 
-For example if your action queues a packet to be processed later,
-or intentionally branches by redirecting a packet, then you need to
-clone the packet.
+   For example if your action queues a packet to be processed later,
+   or intentionally branches by redirecting a packet, then you need to
+   clone the packet.
 
 2) If you munge any packet thou shalt call pskb_expand_head in the case
-someone else is referencing the skb. After that you "own" the skb.
+   someone else is referencing the skb. After that you "own" the skb.
 
 3) Dropping packets you don't own is a no-no. You simply return
-TC_ACT_SHOT to the caller and they will drop it.
+   TC_ACT_SHOT to the caller and they will drop it.
 
 The "environmental" rules for callers of actions (qdiscs etc) are:
 
-*) Thou art responsible for freeing anything returned as being
-TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is
-returned, then all is great and you don't need to do anything.
+#) Thou art responsible for freeing anything returned as being
+   TC_ACT_SHOT/STOLEN/QUEUED. If none of TC_ACT_SHOT/STOLEN/QUEUED is
+   returned, then all is great and you don't need to do anything.
 
 Post on netdev if something is unclear.
-